1. Field of Invention
This invention relates to an animal feed supplement and, in particular, to a buffered feed supplement block for feeding to animals having high volume diets, particularly diets rich in grains.
2. Brief Statement of the Prior Art
Modern practices of feeding beef and dairy cattle include diets rich in grain at high levels of intake to achieve maximum production of milk from cows or gains in weight of beef cattle. Unfortunately, high grain diets cause sharp dips in the rumen pH shortly after ingestion of feed. The resultant fluctuations in rumen pH and the low pH values (about 5.5), disrupt activity of rumen microbes, particularly those which are sensitive to pH.
Prior investigators, e.g., Byers, Schelling and Coppock, Feedstuffs, Sept. 18, 1985, p. 18 report that buffering feed additives such as sodium bicarbonate or a mined ore, which is a mixture of sodium carbonate and bicarbonate, will favorably increase the digestability of high grain diets, although no significant improvements in weight gain or milk production were noted.
Kennelly and French, Univ. Alberta Feeders' Day Report, June 1985, reported that feedings of a diet containing buffers, such as sodium carbonate and magnesium oxide, twelve times a day measurably increased milk production over the same diet fed twice a day. It is also generally believed in the dairy industry that daily feeding of buffers such as one-third pound of sodium carbonate and one-tenth pound of magnesium oxide per cow in an otherwise adequate diet increases milk production by about 5 percent and butterfat content by about 3 percent.
In most dairy operations, there is no convenient method to feed the alkaline buffers. Many dairies feed a dry supplement mix which has barely acceptable palatibility. When buffers are added to the dry mix, the alkalinity of the buffers greatly reduces the palatability of the dry supplement mix, resulting in rejection by the animals.
Ideally, the buffers should be continually available to the animals and should have sufficient palatability that the animals will consume the proper quantities of the buffers by free-choice feeding. This would greatly simplify the feeding operation and would provide the animals with a continuous source of buffer, thus obtaining maximum effectiveness of the buffer.
Feed supplements have been manufactured and marketed as solid blocks which have been fed to cattle on a free-choice basis. A supplement in block form would be a convenient way of feeding buffers on a free-choice basis.
The earliest supplement blocks were pressed blocks which were formed by compressing mixtures of molasses and dry feed ingredients. Prior investigators have included hardening or setting agents in these pressed blocks. As an example, New Zealand specification No. 39247/72 suggests that any water soluble alkaline additive can be added as a setting agents.
Poured blocks, in which the ingredients are mixed with molasses and poured into cardboard cartons where they solidify, are more recent developments. The earliest commercial poured block was prepared by evaporative heating of the molasses similar to candy manufacturing as described in U.S. Pat. No. 3,961,081. This block lacked water resistance, and melted at elevated storage temperatures.
The most recent advances in supplement have been the poured chemical blocks, in which additives are used to gel molasses and form water-resistance solids. Large amounts of calcium oxide or magnesium oxide have been added to molasses and the mixtures have been heated to form solid supplements in the manner described in New Zealand Patent Specification No. 170,505.
Entirely chemically gelled and hardened poured blocks and their manufacture are described in U.S. Pat. Nos. 4,027,043, 4,160,041 and 4,431,675. These blocks are prepared by the reaction of molasses, a soluble phosphate and the oxide or soluble salt of calcium and/or magnesium. No heating is required and the liquid mixture is poured into cardboard cartons for solidification. Maximum hardness is attained by using both calcium and magnesium oxides.
Another method of manufacture of a poured block is described in U.S. Pat. Nos. 4,171,385 and 4,171,386 in which the molasses is gelled with clay which is added with high shear agitation. Magnesium oxide is added to the liquid mixture and the hardness of the block can be increased by the addition of ferrous sulfate, as described in U.S. Pat. No. 4,265,916.
The feed blocks which have been developed for free choice feeding of range cattle generally are far too hard for feeding to cows in a well managed dairy, or to beef cattle in a feed lot. Additionally, buffers such as sodium carbonate or bicarbonate cannot be readily added to these blocks without adversely affecting their quality. Well-fed cows or beef cattle will not consume a sufficient quantity of these blocks because of their hardness and/or lack of palatibility.